You probably think no one is paying attention to your problem, but you'd be wrong. I myself have looked it over and over again, and thought about it over and over again, but like you, came up with nothing. And I'm sure that other folks here also tried to help.
Permit me, however, to offer my method of diagnosis. Maybe it helps; maybe it doesn't. When you suspect a particular part is the cause of your problem, for instance, the spark plug, and replacing the spark plug doesn't help, make sure to reverse your change, that is, to reinstall the original plug. Your goal in diagnosis is to disqualify possible problems, what I call "lessening the variables". If you were to change the spark plug, and seeing no improvement, leave it in and continue looking for the problem, you just introduced another variable, namely, the new plug, rather than removed a variable. Maybe the new plug is bad. At least with the old plug, you're no worse off than where you started and can continue the quest. It may seem like a waste of time, particularly if the component in question eats up a lot of time to remove and to install it, but in my experience, it's worth it to avoid introducing new variables.
One more point: a functional ignition will produce a spark even when the flywheel is turned by hand. Work at night. Take out the spark plug so it's easy to turn the flywheel. Position the flywheel magnet just before the point at which it should cause a spark. Position the spark plug wire near a good ground. Turn off the lights. Manually move the flywheel a few inches back and forth, repeatedly letting the magnet pass the coil. On a small engine, it's easy to get the magnet going fast enough that you'll see a spark. But you need darkness to see it.
I'm sorry if none of this answers your question.